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| |
| #include "qv4memberdata_p.h" |
| #include <private/qv4mm_p.h> |
| #include "qv4value_p.h" |
| |
| using namespace QV4; |
| |
| DEFINE_MANAGED_VTABLE(MemberData); |
| |
| static size_t nextPowerOfTwo(size_t s) |
| { |
| --s; |
| s |= s >> 1; |
| s |= s >> 2; |
| s |= s >> 4; |
| s |= s >> 8; |
| s |= s >> 16; |
| #if (QT_POINTER_SIZE == 8) |
| s |= s >> 32; |
| #endif |
| ++s; |
| return s; |
| } |
| |
| Heap::MemberData *MemberData::allocate(ExecutionEngine *e, uint n, Heap::MemberData *old) |
| { |
| Q_ASSERT(!old || old->values.size <= n); |
| if (!n) |
| n = 4; |
| |
| size_t alloc = MemoryManager::align(sizeof(Heap::MemberData) + (n - 1)*sizeof(Value)); |
| // round up to next power of two to avoid quadratic behaviour for very large objects |
| alloc = nextPowerOfTwo(alloc); |
| |
| // The above code can overflow in a number of interesting ways. All of those are unsigned, |
| // and therefore defined behavior. Still, apply some sane bounds. |
| const size_t intMax = std::numeric_limits<int>::max(); |
| if (alloc > intMax) |
| alloc = intMax; |
| |
| Heap::MemberData *m; |
| if (old) { |
| const size_t oldSize = sizeof(Heap::MemberData) + (old->values.size - 1) * sizeof(Value); |
| if (oldSize > alloc) |
| alloc = oldSize; |
| m = e->memoryManager->allocManaged<MemberData>(alloc); |
| // no write barrier required here |
| memcpy(m, old, oldSize); |
| } else { |
| m = e->memoryManager->allocManaged<MemberData>(alloc); |
| m->init(); |
| } |
| |
| m->values.alloc = static_cast<uint>((alloc - sizeof(Heap::MemberData) + sizeof(Value))/sizeof(Value)); |
| m->values.size = m->values.alloc; |
| return m; |
| } |